The Panopticon/Real world animals?

Is it just me or do we not have any real world categories for animals? We have them organised in terms of earth, but earth doesn't equal from the real world. Human Badgers are Earth mammals but they are NOT mammals from the real world. It seems to me, looking through the categories that in some places we organise things by real world and everything else, but in other places we organise things by earth ans everyone else. Is there a reason behind this? Because I find it very confusing how Earth and Real world are sometimes but not always treated as interchangeable and sometimes but not always treated as the way to organize pages.